Pressure washers or power washers are power cleaners. The powerful spray of water coming from a pressure washer ensures effective cleaning of any kind of surface- wood, concrete, glass or fiber. The main component in a pressure washer is the pump, which creates water pressure inside the machine. This pressure can be adjusted according to the need. The house contains a trigger, which allows for adjusting the pressure of the water further from short bursts to a continuous spray.
Source: http://www.lawncarepal.com/15-best-pressure-washers-reviews-of-2016